Cellulose xanthate as a soil conditioner: implications for weed control with some soil-applied herbicides

Applications of cellulose xanthate equivalent to 50 kg cellulose/ha to fresh seedbeds preserved surface microtopography and prevented capping after rainfall. Numbers of weed seedlings were up to 50% greater than on untreated soil where capping occurred. The efficiency of nine soil-acting herbicides was not impaired when applied at normal rates either before or after cellulose xanthate. There was no evidence of interaction and the numbers of surviving weeds were proportional to the numbers where no herbicide had been applied. With propachlor, however, weed control was consistently less when applied shortly before or after cellulose xanthate, and analyses showed that in the presence of the soil conditioner the rate of herbicide loss was enhanced. This effect decreased the longer propachlor application was delayed, but was still evident with an interval of 96 h.